The development of the biorefinery industry has enabled and improved the eco-friendly production of several industrial chemicals with a reduced dependency on petroleum resources. As an example, the microbial production of 2,3-butanediol as a platform chemical has attracted great interests, due to its large potential in industrial applications (Ji et al., 2011). Therefore, several bacterial species, such as Klebsiella pneumonia (Ma et al., 2009), Serratia marcescens (Zhang et al., 2010) and Enterobacter aerogenes (Jung et al., 2012), have been developed as industrial strains for 2,3-butanediol production.
The price of the carbon source accounts for a large portion of the cost of microbial 2,3-butanediol production. Therefore, there have been many efforts to find cheap substrates. Sun et al. (2009) reported that Klebsiella pneumoniae produced 91.63 g/L of 2,3-butanediol from pretreated Jerusalem artichoke tubers by fedbatch simultaneous saccharification and fermentation (SSF). Wang et al. (2010) used corncob molasses, a waste byproduct in xylitol production, for 2,3-butanediol production, where 78.9 g/L of 2,3-butanediol was produced by K. pneumonia after 61 h of fed-batch fermentation. Jiang et al. (2012) tried to produce 2,3-butanediol from acid hydrolysates of jatropha hulls, where a two-step hydrolysis was applied to effectively hydrolyze the jatropha hulls, and 31.41 g/L of 2,3-butanediol was achieved by Klebsiella oxytoca. 
In 2008, the USDA reported that the price of sugarcane molasses was less than $0.50/kg (Chan et al., 2012). Sugarcane molasses contains a few mixed sugars, a dominant amount of sucrose, and similar amounts of glucose and fructose (Akaraonye et al., 2012). Therefore, the efficient utilization of sucrose is necessary in order to maximize the use of sugarcane molasses. A sucrose utilization pathway has been studied in enteric bacteria. As shown in FIG. 1a, the transport and catabolism of sucrose can be classified into two routes: the phosphotransferase system (PTS) and non-PTS (Reid and Abratt, 2005). A PTS-dependent transporter imports sucrose with phosphorylation by Ellscr, which was characterized in K. pneumonia as scr operon (Sprenger and Lengeler, 1988). Meanwhile, a non-PTS permease transfer of sucrose into the cell without chemical modification has been determined in Escherichia coli as csc operon (Bockmann et al., 1992). In K. pneumonia, the operon consisted of five open reading frames, encoding fructokinase (ScrK), sucrose-specific outer membrane porin (ScrY), PTS EII transport protein (ScrA), sucrose-6-phophate hydrolase (ScrB) and sucrose dependent regulator (ScrR) (FIG. 1b). The transcription of scr operon was repressed by ScrR. However, the effect of scrR mutation on the utilization of sugarcane molasses has not been reported yet.